CDC Warns About Reemergence Of Swine Flu In U.S.The Centers for Disease Control and Prevention is reporting new cases of new swine flu infection. It has issued warnings for people to take steps to protect themselves from the virus.

The Centers for Disease Control and Prevention is reporting new cases of new swine flu infection. It has issued warnings for people to take steps to protect themselves from the virus.

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Federal health officials today issued a warning for something we don't usually think about in August: the flu. NPR's Rob Stein reports on a worrisome jump in the number of Americans getting infected with a new swine flu virus.

ROB STEIN, BYLINE: There are lots of different kinds of flu viruses out there. Some infect people, others infect animals like pigs. Whenever a pig virus jumps to a person, public health officials take notice. That's because when a new virus comes along, most people have no immunity against it, and it could easily be deadly.

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Joseph Bresee, at the Centers for Disease Control and Prevention. He says a new swine flu virus showed up in humans in this country about a year ago.

JOSEPH BRESEE: The virus was first detected in humans July of 2011, and since July 12, 2011 there have been 29 total cases.

STEIN: What has officials concerned now is that 16 of those cases were confirmed in just the last three weeks, including at least a dozen in just the last seven days or so, in Ohio, Indiana and Hawaii. Now, almost all the infections have been in people who had close contact with pigs, mostly kids at county fairs. And officials aren't too worried because the virus isn't spreading easily from person to person. If the virus becomes highly contagious, that could spark a pandemic. Here's the CDC's Joseph Brezee again.

BRESEE: Importantly, sustained transmission of this virus has not been detected to date. And therefore, we are not seeing features consistent with an early influenza pandemic.

STEIN: But that's always a possibility. So, officials are on high alert.

BRESEE: Because influenza viruses are always evolving, we will watch closely for signs that the virus has gained an increased capacity for efficient and sustained human-human transmission.

STEIN: In the meantime, the CDC is asking people to take precautions. Stay away from any pigs that look sick and do things like make sure your child washes their hands really well after petting a pig at a local fair. Rob Stein, NPR News.

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